Transition Metal Chemistry

, Volume 9, Issue 8, pp 294–299 | Cite as

Phenolate complexes of iron(III) in dimethylsulphoxide solution

  • Juan Faus
  • José M. Moratal
  • Manuel Castelló
Full Papers


The formation of complexes between Fe3+ and 2,4-dinitrophenol, 4-nitrophenol and 4-methylphenol is studied in dimethylsulphoxide solution. The reaction proceeds almost to completion and the occurrence, in solution, of complexes with higher stoichiometry than 1∶1 is reported for the first time. The following stability constants are determined (25 °C, 0.1 M KClO4): FeIII-2,4-dinitrophenolate β1=1.8×103, β2=4.4×105; FeIII-4-nitrophenolate β1=1.10×107, β2=2.5×1012 β3=3.9×1016; FeIII-4-methylphenolate β=1.7×1012.

The binding of a phenolate ligand to iron(III) strongly decreases its affinity for other phenolate ligands. The superior σ-donor, 4-methylphenolate (OC6H4Me), only forms a 1∶1 complex, Fe(OC6H4Me)2+. The e.s.r. spectrum of this species clearly prove it is a true iron(III) complex and does not contain iron(II), in opposition to recent claims. However, the complex Fe(OC6H4Me)2+ easily undergoes a ligand-to-metal electron transference. Addition of an excess of 1,10 phenanthroline yields the iron(II) complex [Fe(o-phen)3]2+ instantaneously.


Iron Physical Chemistry Phenolate Inorganic Chemistry Electron Transference 
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Copyright information

© Verlag Chemie GmbH 1984

Authors and Affiliations

  • Juan Faus
    • 1
  • José M. Moratal
    • 1
  • Manuel Castelló
    • 1
  1. 1.Departamento de Quimica InorgánicaFacultad de Química de la Universidad de ValenciaSpain

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